September 15th, 2020 Update: A new highest temperature (year-to-date) has been recorded) on September 14th, 2020.
Light winds, mostly sunny skies (at the start of today) and abundant moisture led to today being the hottest day for 2020 across Trinidad, based on temperatures recorded at Piarco. This is the climate reference site for Trinidad, while across Tobago, the climate reference station is at Crown Point.
On Saturday, across most of the country, temperatures between ranged between 30.0°C and 35.0°C, with some areas between 35.0°C and 37.0°C, mainly across Trinidad. In urban areas and areas where development is prevalent, temperatures trended higher.
Because of elevated moisture moving across the islands due to Tropical Storm Josephine to our north, the heat index or what outside felt like was higher than usual.
The maximum recorded temperature occurred at the Piarco International Airport, came in at a scorching 34.6°C, recorded by the Trinidad and Tobago Meteorological Service. Since this is the official temperature monitoring station for T&T’s records, this marks the hottest temperature for the year to date, beating the previous highest maximum temperature at Piarco on April 27th.
Temperatures in cities, such as Port of Spain, tend to be much higher than surrounding locations due to a phenomenon called the Urban Heat Island Effect. There are several causes, but the main instigator for this phenomenon tends to be increased dark surfaces such as roads and pavement in cities, which absorb solar radiation more than surrounding areas.
Where do these temps stand compared to our records? The hottest recorded in Trinidad, based on data from the Global Historical Climatology Network (pre-1980) and the Trinidad and Tobago Meteorological Service (1980-2019) stands at 37.8°C recorded on April 20th, 1946 at Wallerfield.
At Piarco International Airport, where the new official records began, the hottest temperature for the year was recorded on September 25th, 1990, at 36.5°C.
The Heat Index
Several persons across the country took to social media to complain about the heat, or more so what outside felt like. This is called the heat index and is a combination of air temperature and relative humidity, determining what the air feels like to a person i.e., how hot it actually feels.
The heat index is important because of sweating. Your body sweats to cool the skin and maintain a constant, healthy body temperature. This cooling process means that the sweat has to evaporate off the skin to remove heat. However, if the sweat is unable to evaporate, the body isn’t able to regulate temperature.
With high volumes of moisture in the air, also known as high relative humidity, which T&T regularly experience due to its tropical climate, the rate of sweat evaporation decreased. This is because the atmosphere is unable, or has limited potential to hold additional moisture in the atmosphere.
This results in you feeling warmer in humid conditions and cooler in less humid conditions i.e. when relative humidity decreases. As temperature increases, the heat index increases. As relative humidity increases, so does the heat index.
Heat index is generally classified into four categories: caution, extreme caution, dangerous, and extremely dangerous. Generally, across Trinidad and Tobago, we experience heat indices of caution to extreme caution in times of hot days, with isolated areas experiencing dangerous heat indices such as urban areas.
High Temperatures To Continue
Cooler conditions are forecast in the short-term due to the ITCZ remaining across the region through the first half of the upcoming week.
However, In the Trinidad and Tobago Meteorological Service’s (TTMS) Rainfall and Temperature Outlook for Trinidad and Tobago, issued on Friday 31st, July 2020, hotter days are in the forecast.
Usually, the peak of Trinidad and Tobago’s heat season runs from August to October. In most years September is the hottest month. August through October 2020 is likely to be warmer than usual with both day and night temperatures expected to exceed their averages. There are concerns for short duration hot-spells and hot days (days with a maximum temperature greater than 33.9oC in Trinidad and greater than 32.0oC in Tobago) remain elevated for August through October 2020.
“There is greater than 75 % chance for maximum day-time and minimum night-time temperatures to be above average, with September days and nights likely to be the warmest during the period,” based on the TTMS’s outlook.
Is this a heatwave?
Currently, tomorrow’s forecast maximum high temperature is forecast to be near 34.0°C in Trinidad and 33.0°C in Tobago. Today was an isolated event with hot temperatures, as will be tomorrow if the forecast temperatures materialize.
For a hot spell to be declared in Trinidad and Tobago by the Trinidad and Tobago Meteorological Service, a period of hot temperatures, characterized by maximum temperatures of at least 34.0°C in Trinidad and 32.0°C in Tobago, lasting five or more consecutive days. A short-duration hot-spell is three or more consecutive hot days.